Luis Méndez de Haro (born February 17, 1598,Valladolid, Spain—died November 26, 1661, Madrid) was the chief minister and favourite of KingPhilip IV (reigned 1621–65), who failed to stem the decline of Spanish power andprestige.

Haro’s political career advanced under the patronage of his uncleGaspar Olivares, who was chief minister during 1621–43 and whom he succeeded when Olivares fell from favour. Shortly thereafter the era of Spanish military preeminence ended with the defeat at theBattle of Rocroi (May 1643). Haro was able to claim success in the suppression of rebellion inSpain’s Italian possessions, but he could not arrest economic decline and consequent social distress. He also failed to subdue the rebellious Portuguese or stem English colonial encroachments. Haro gained moderate terms in thePeace of the Pyrenees (1659), which ended the longwar with France; nevertheless, Spanish power was on thewane.